The technical book “Handbuch Verbrennungsmotor” [“Internal combustion engine handbook”], edited by Richard von Basshuysen, Fred Schäfer, 2nd edition, Vieweg & Sohn Verlagsgesellschaft mbH, June 2002, pages 79 to 80, discloses a dual-mass flywheel which has a first centrifugal mass rigidly coupled to the crankshaft of the internal combustion engine, and a second flywheel mass coupled to the transmission via a clutch. The first flywheel mass and the second flywheel mass are coupled to one another in a rotationally elastic manner by means of springs. Here, firstly the non-uniformities resulting from imbalances of the moving masses in the drivetrain and secondly the rotational non-uniformities resulting from the movements of the pistons of the internal combustion engine can be damped by means of the springs. Good vibrational characteristics of the drivetrain and therefore a high level of driving comfort can thereby be achieved.
The dual-mass flywheel may be described as a spring-mass system. It has a natural frequency dependent on the spring constants, on the masses of the first and second centrifugal masses and on the friction values.
At certain rotational speeds of the internal combustion engine, resonances may arise which may have repercussions on the running smoothness. The resonant frequency generally lies below the idle rotational speed. During starting and stopping of the internal combustion engine, said range is normally passed through so quickly that said resonances do not arise. Operation within said rotational speed range with resonance of the dual-mass flywheel may however occur if for example the starter is disengaged too early during starting, or if, during operation, the internal combustion engine is forced below its idle rotational speed with the clutch. Secondly, operation within said rotational speed range may occur without resonance arising, for example during starting of the internal combustion engine at very low temperatures.
In the event that resonance arises, suitable intervention into the control of the internal combustion engine should take place in order to prevent damage to the dual-mass flywheel. Said interventions should substantially reduce the torque of the internal combustion engine, for example by shutting off the injection. In the event that the internal combustion engine is running in the corresponding rotational speed range without resonance arising, however, a reduction in torque or even shut-off of the injection must not take place because otherwise, for example, a start of the internal combustion engine at low temperatures would not be possible.